Online slot glossary: Everything you need to know and more

Online slot glossary: Everything you need to know and more
Pavlos Sideris
by Pavlos Sideris Last updated:

The ultimate online slot glossary

Slots and the websites hosting them have come a long way since the days when all the player had to do was push a single button. In fact, online slots have become so advanced, with various mechanisms, features and formats, that they can seem a bit overwhelming for newcomers. 

Still, understanding the relevant lingo and jargon is an important part of being a responsible player and getting the most out of your online gaming.

As slots continue to evolve in this way, so does the terminology. And so the Slot Gods team has compiled and bestowed upon you a comprehensive A-Z glossary, fully updated for 2024!

Online slot glossary A-Z 

3-Reel Slot: An online slot with 3 active reels, across which winning symbols can land.

5-Reel Slot: Similar to 3 reels, except the game area is bigger, usually meaning bigger win potential.

Active Payline: How many paylines are currently active during a single spin – most games have fixed paylines set in place.

All Ways: All Ways slots have paylines that pay out from left to right of the reels as well as from left to right. Slots that offer All Ways wins are arguably more popular than those with regular paylines.

Annuity: If a player was to win a large jackpot they may well be paid in annuity, which is where the money is paid over the course of many months or years, rather than as a lump sum.

Area Wins: Some slots pay when a number of symbols fall within a specific area on the grid rather than a payline or a cluster.

Autospin: Is a feature that allows the game to automatically play on its own for a predetermined number of spins, set to specific terms. Not available in the UK.

Avalanche: See Cascading Reels. Some slot developers refer to this as an avalanche.

Balance: The amount of credit in your casino account.

Bankroll: Refers to how much money an individual player has/is willing to play with.

Base Game: When referring to the base game, we are talking about the standard online slot gameplay without any bonus rounds being unlocked.

Bet: The amount of money the player will wager on a spin.

BGC: Betting & Gaming Council, the standards body for the regulated UK betting and gaming industry, excluding the National Lottery.

Big Hit: Another term for a player enjoying a big win/large payout from an online slot. 

Bonus Credit: If you’ve picked up a deposit bonus, you’ll be given a lump sum of bonus cash to spend. This is kept separate from your real cash balance and often has wagering requirements and other bonus terms and conditions attached.

Bonus Feature: A bonus feature is built into an online slot to make it more lucrative to play and helps it stand out from other online slots. The feature might be something as simple as special symbols, or it might be something bigger such as a unique bonus round.

Bonus Round: Is a special round in an online slot game usually unlocked by landing three identical special symbols across the reels known as scatter symbols. These rounds are free spins or unique mini-games that usually see players win significantly more money than they would during the base game.

Buy Feature: The Buy Feature, also known as a 'buy-in' is a mechanic built into online slot games that allows players to jump straight to the game’s bonus round for a set amount of money. UK players can't use the Buy Feature since it was banned by the Gambling Commission.

Branded Slot: A slot based on a real-life entity, such as a popular television or game show. Examples include Narcos, Monopoly Megaways and Deal or No Deal Lightning Spins.

Cascading Reels: An online slot mechanic in which winning combinations are removed from the game reels only to be replaced by symbols from above.

Cashback: An incentive offered by some casinos that sees players win back a proportion of the money wagered while playing earlier that week.

Cluster Pays: Some slots present a different setup with wins forming in a cluster of symbols that touch horizontally or vertically.

Coins: Rather than show players their balance in an online slot, some games will convert it into coins, which are used as an alternative betting currency for that game alone.

Coin Size: The amount of money being wagered on a single spin.

Cold Slot: A slot referred to as a ‘Cold Slot’ isn’t paying out very often and is on a bad streak. This may well be because it has recently paid out a large sum of money.

Collect: Often seen in old-school slot machines and some older online slot games, the collect button allows players to collect their winnings, transferring it into real cash / their balance. 

Credits: Rather than show players their balance in an online slot, some games will convert it into credits. Essentially the same as coins. 

Denomination: Is the amount of money (or the number of coins or credits) a player is wagering per spin.

Expanding Wilds: Expanding Wilds are Wild symbols that expand to fill an entire reel, rather than being just one single symbol. Expanding Wilds may lead to many much larger wins.

Features: Bonuses and other special areas of the game are features that enhance the gameplay and usually the win potential too.

Fixed Jackpot: A fixed jackpot will always pay out the same fixed amount. This is regardless of how often the jackpot is won or how many players are playing it at any given time.

Free Spins: Free spins are exactly as the name suggests – spins on an online slot that do not cost the player any money. These can be gained through an online slot bonus game or via a casino promotion or welcome offer

Fruit Machine: A fruit machine is the name of the classic physical slot machines often found in pubs in the UK. The name comes from the fruits symbols on the reels.

Gamble: The act of wagering money in the hope of winning something back.

Gamble Feature: A mechanic built into some online slots that allow players to gamble the money earned from a winning spin to double, or quadruple it. More often than not this is done by picking the correct colour or suit from a deck of playing cards. 

Grid Slot: Not all slots require standard reels. A 6x6 grid, for example, might be used to offer Scatter, Cluster and Area wins.

Hit: Hit is another term for a winning spin.

High Volatility: High volatility online slots are slots that tend to pay out large sums of money occasionally – the flipside is that small wins are also infrequent.

Hot Slots: Hot slots are games that players perceive to be on a ‘hot’ streak which are generously paying fast and often. 

iGaming: The term given to the online slots industry as a whole. 

Jackpot: Refers to the top prize of an online slot game. It could also refer to a separate jackpot linked to the slot that can be triggered randomly during gameplay.

Jackpot Slot: Is an online slot that has a lucrative jackpot built into it that can be won at any time. Even though the top prize of a slot is referred to as a jackpot, not all slots are considered jackpot slots.

Low Volatility: Low volatility online slots tend to pay out smaller sums of money to players at more regular intervals compared to medium and high volatility slots.

Max Bet: The maximum you can wager when playing an online slot; the largest amount of coins you can bet across the greatest number of paylines.

Megaways: Megaways are a type of online slot  with dynamic reels developed by Big Time Gaming. They offer players 117,649+ ways to win (paylines).

MGA: The Malta Gaming Authority, a respected regulatory body that licences a number of online casinos and online slot developers to operate. 

Modifiers: Are ways of enhancing regular wins – Multipliers are a good example. This term is often interchangeable with features.

Multiplier: Is a bonus feature that some online slots incorporate into their games. These multiply players' winnings by a set amount. A 2x multiplier would see winnings doubled, whilst a 4x multiplier would see winnings quadrupled, and so on.

Min Bet: The smallest possible bet a player can make using the minimum amount of coins across the minimum amount of paylines.

Payline: Is an invisible line that runs across the game screen. If several matching slot symbols appear along one of these invisible lines, then a win is awarded.  

Payout: Is when a player receives money (their winnings) for successfully landing a winning spin on an online slot.

Paytable: Is a screen found on all online slots that explains each symbol's value based on how many land on the reels at any given time.

Penny Slots: Are online slots that allow players to bet just a single penny as the minimum bet – perfect for players with a low bankroll.

Pick and Click / Pick a Win: Pick and Click is a type of bonus built into some online slots. Players are shown a number of symbols with prizes hidden behind them and must pick one or more, clicking on them to reveal a prize. 

Pokies: Australian slang for slot machines.

Progressive Jackpot. Is a jackpot that slowly builds in value as numerous players from around the world wager money on it. A small percentage of each player’s bet goes towards growing the overall jackpot prize.

Random Number Generator (RNG): The measure built into every online slot and physical slot machine. It determines what symbols will appear on the reels on any given spin. A spin made with RNG is guaranteed to be completely random and near impossible to predict.

Reels: Are the most important element of any online slot. Every online slot has a set of reels adorned with game symbols. When players make a wager, the reels spin and come to a stop on their own, determining whether the player has won or lost.

Rows: Are horizontal lines of symbols on the reels.

Return to Player (RTP): Indicates the percentage of money players can expect to win back from the casino over time. 100% Return to Player would mean players' chances of winning money are equal to that of the casino. On average most fair online slots have an RTP around 96%, meaning over a significant period of time £0.96 would be paid back against every £1.00 wagered. RTP can vary wildly based on mechanics and jackpots.

Scatter Symbols: A scatter is a special symbol that many online slots utilise. When three scatter symbols land on the reels, they activate the game’s bonus / free spins round. Scatters occasionally have their own payout for a group of 3+.

Slot Tournament: An event in which players can enter a competitive environment to win the most money or hit certain achievements. 

Spin: A spin occurs when the player hits the play button on an online slot. The reels spin and stop on their own, revealing whether the player has won or lost.

Stake: Another word for the bet you place on each spin.

Streak: As in 'winning streak' is when a player registers several wins in a row. 

Symbols: Are the images on the reels of an online slot. Players must match symbols in order to register a winning spin. 

Tumble: See Cascading Reels. Some slot developers refer to this as a Tumble.

UKGC: The United Kingdom Gambling Commission – world-renowned regulatory body that issue licences to online slot sites and slot developers operating in the UK.

Variance: Also known as volatility, refers to the predictability of an online casino game, concerning the size of wins and frequency of payouts.

Video Slot: Is the name given to online slots that grew in popularity alongside the growth of the internet. These slots make use of animated reels rather than physical ones and feature flashy and exciting bonus mechanics. 

Volatility: Also known as variance, refers to the predictability of an online casino game and the size and frequency of payouts you should expect.

Wager, a: An alternative word for a bet. Players place a wager on an online slot every time they opt to make a spin.

Wager, to: The process of placing a bet.

Wagering Requirements: Are a condition that online casinos impose on bonuses in order to prevent players from abusing them. It means players have to play through a bonus/winnings multiple times before withdrawing.

Wild: Is a special symbol in online slots that automatically substitutes for any other symbol in-game (other than scatter symbols). Wilds can lead to lucrative wins. 

Winning Combination: Is when the reels stop and there are a number of matching symbols that form a win, according to the game's pay structure.


Do all slots use paylines?

Paylines, which determine where a winning combination of symbols can fall, are used by many slots. They can be a single horizontal line, or they might form a random pattern. Some slots go against the payline mechanic and offer more innovative ways to land a prize, such as grid slots and Megaways games.

How can I view a slot’s paylines?

The number of paylines and their layout can change based on the player’s wager. You should be able to see these variable paylines in the game’s paytable, found on the information page. This is often denoted by an ‘i’ symbol, and is accessible in-game.

Why can’t I auto-spin?

In 2021 the UKGC announced the banning of the auto-play function in slots. This shift in policy was the result of concerns that auto-spinning caused some players to lose track of their gameplay, thus encouraging unhealthy habits.

How do I trigger a slot's bonus game?

Taking advantage of bonus features is a big part of getting the best out of slots. A bonus game/round is typically unlocked by landing three bonus symbols on an active payline. This can vary from one slot to the next, as can the actual symbols used, so it’s best to check the information page before playing. 

What is considered a good RTP?

The UKGC has no minimum requirements regarding RTPs, but operators are obliged to display the RTP to the player, so always be sure to check when trying out a new game. It is generally accepted that anything above 96% is fair, so anything lower than this should be viewed with caution (unless you're playing a game with a big jackpot). Some slots’ RTPs are in the 99% region, so keep an eye out for these.

Is low or high volatility better?

Volatility, also known as variance, is a matter of personal preference. Whilst a low volatility game will pay out more frequently, a high volatility game offers more substantial, less frequent wins. The overall RTP is not affected by a slot’s volatility level.

Which are the biggest jackpots?

Whilst many slots offer fixed jackpots, the biggest wins come from progressive jackpots which are shared across a network. For example, Mega Moolah and WowPot jackpots account for the largest online slots wins of all time. 

Are 3 or 5 reels better?

Generally speaking, more reels means bigger winning combos. For this reason, 5-reel slots are generally more popular than their less complex 3-reel counterparts, but some players enjoy the relative simplicity of a 3-reel slot.

Pavlos Sideris
by Pavlos Sideris Last updated:

Pavlos has loved playing slots since he was tall enough to stand at a fruit machine. With over 10 years’ experience in the industry he’s been around long enough to remember when flash games and downloadable casinos were as good as it gets!